Generally, the data, arising from these representations, are correlated with cartographic data. They can be of meteorological or topological type, for example.
The device according to the invention introduces an ergonomic of various graphical representations overlaid notably by color and transparency rules which depend on the data themselves.
Currently, equipment dedicated to graphical representations of the aircraft-related environment and of the aircraft-independent environment exists in aircraft such as civil and military airplanes or helicopters.
The systems for representing the aircraft-related environment depend on data specific to the aircraft, such as the system data, the trajectory, the altimetry data or the resources of said aircraft. The pilot is constantly informed of these data. These data are paramount for navigation and are calculated and refreshed at each cycle of calculations of the avionics computer. They can, notably, serve for other applications which require information specific to the aircraft in the guise of input data to perform other calculations. These data may typically be the heading of the aircraft or its position in space, for example.
To enable the pilot to navigate with a knowledge of the environment in order to minimize the dangers, the data related to the environment of the aircraft are correlated with the environmental data independent of the aircraft. These data can be of the topological or meteorological type, for example. They can arise from a database, such as terrain data or be captured, calculated and processed in real time, such as meteorological data or terrain collision predictions.
Correlation of these data makes it possible, for example, to ascertain and to predict, for a determined heading and a known trajectory, the potential dangers related to the situation of the aircraft in its outside environment. The prediction is evaluated in the near future with the assumption that the heading and the trajectory of the aircraft remain unchanged. Viewing screens or alarms are customarily used to alert the pilot.
One of the main benefits of such functions is to evaluate potential risks, notably, of collisions, of strong turbulence or else of lightning which would cause a decline in flight safety.
Several systems exist for representing the aircraft-related environment, which each depend on the data specific to a given application.
An exemplary existing system for analyzing environmental data is the WXR system, the trade name given to the product developed and marketed by Rockwell Collins, and standing for “Weather Radar System”. This equipment is used in numerous aircraft. It consists of a radar antenna, which permanently scans an angular sector situated in front of the carrier over a parametrizable distance. This equipment analyzes the atmosphere to recover meteorological data and provide them to the pilot.
On the basis of the data acquired in real time, the WXR equipment is capable of providing digitized meteorological information to the other systems of the carrier. This information then makes it possible, in the case of cockpit display systems, to depict the sector scanned on a screen and thus to display to the crew the meteorological information in relation to the position of the carrier.
Moreover, another exemplary case of such systems is the TAWS system, the acronym standing for “Terrain Awareness Warning System”. The system has been developed and marketed by Thales in collaboration with L-3 Communications, under the name T2CAS.
More generally, TAWS is a system which, with respect to altimetry data, arising from a numerical database, generates a graphical display and if appropriate audible alarms on the basis of a calculation which takes into account:                the position of the carrier, as well as various flight parameters, notably its speed and its heading;        the extrapolations of the trajectory of the carrier in order to perform prediction calculations;        the characteristics of the carrier in terms of performance, notably as regards the emergency climb phases at maximum performance.        
On completion of this calculation, the TAWS advises the crew, graphically or in the form of audible alarms, of:                the altitude slice in which the carrier is situated in relation to the terrain round about        the zones of the terrain which may over a short timescale endanger the safety of the flight if the crew does not modify the trajectory of the carrier        the zones of the terrain which endanger the safety of the flight if the crew does not immediately modify the trajectory of the carrier.        
The TAWS is a function which is embedded in real-time avionics computers.
Another exemplary application is the terrain topology cartographic representation system. This system, by means of a known numerical database, constructs a graphical representation of the terrain and its attributes, such as shade, vector data and obstacles.
In particular, in aircraft, the graphical representation of the terrain is servoed for a given calculation cycle by the carrier's current position and with respect to its heading. Several modes of representing the terrain and positioning the carrier on the terrain are available depending on the operational contexts.
As regards the harmonization of the graphics, arising from the various applications, the structure of the data and the discretization of the information depends notably on each application and the protocols used. For example the TAWS and WXR applications structure their digital data according to radials.
Moreover, the cartographic function uses another mode of data structure.
Within this framework, FIG. 1a represents the digitization of information collected, in space or from a database, in the form of radials. A radial 5 is oriented along an angle close to the heading of the aircraft. In the TAWS application, the radial possesses a range 3 corresponding to the most distant point in the digitized zone. This radial comprises a certain number of points 1. Each of the points digitizes an item of information, notably calculated on the basis of the altitude of the measured point. The point represents notably a danger for the aircraft in the near future if the heading does not change. The point belongs to a zone which possesses a color code which indicates to the pilot the potential danger in the direction of the radial. The radials possess a spread, represented by an angle 2. At a given distance from the aircraft, the point discretizes the danger in a perimeter included in the angle 2 and between the point downstream and the point upstream of the point considered.
The TAWS application refreshes a set of radials in a determined calculation time and presents them to the pilot in graphical form. FIG. 1b represents a set of radials digitizing a part of space forming an angular sector, situated in front of the aircraft.
FIG. 2 represents a graphic of an example of the TAWS application. It represents an angular sector 22 digitized by points of each radial. Each point represented comprises a color information cue relating to danger, said danger being estimated on the basis of the aircraft's altitude extrapolated into the near future. This angular sector therefore comprises zones of various hues or colors. This zone covers a wide angle centered on the heading of the aircraft 23. Certain hues 20 represent a danger if the aircraft steers towards this zone, other hues 21 signify that no danger of collision is visible in this direction.
FIG. 3 represents a mapping 30 of the relief that the aircraft is overflying. The zone 31 represents a relief which could be a mountain or a hill, the zone 32 represents a space of low relief.
A drawback of the solutions such as developed, are their relative independence and their exclusive use which makes it necessary for example to integrate as many viewing screens as applications into the flight cabin. For example, each of the aforementioned three applications, the mapping application, the meteorological application, and the altimetry application, possesses dedicated graphical resources and a dedicated display.
The exclusivity of the applications requires the pilot either to manually change graphical representation on one and the same screen according to the application, or to track various screens during the piloting phase.
In the case of an overlaying of graphical representations, a major drawback amounts to choosing the representation which is displayed by priority to the pilot. In the case of an overlaying of data arising from different applications, the problem of the possible masking of certain data by a graphic can constitute a significant drawback.
These aforementioned drawbacks become yet more crucial when it is necessary to recognize danger zones for the aircraft. The danger rating of a geographical zone evolves continually during a flight performed by an aircraft. The representation of the zones of risk or danger of a given application is not differentiated in the priorities of display of the graphical representations which are overlaid.